This invention relates to a tension mechanism to place a predetermined length of wire used to drive original scanning carriers under an appropriate tension in various image processors such as copying machines, printers and scanners. These image processors read images of an original represented on a paper sheet or the like and then subject these images to various kinds of processing.
The function of carriers in an image processor is to pick up images to be processed from the original and to guide them to an image processing unit such as a CCD. To achieve this, the carrier is provided with a reflector or the like adapted to form an optical path extending from the original to said CCD. The carrier thus scans the original and picks up the images on said original. The carrier is operatively associated with a wire taken up on a pulley by a motor so that said scanning is performed as said wire travels. One end of the wire is attached to the inner wall of the housing containing said carrier. The other end of the wire is also attached to the inner wall of the housing but with the interposition of a tension spring, for example, in the form of a tension coil spring so that the tension spring places the wire under a tension required for properly driving the carrier. An intermediate length of the wire is draped directly on the carrier or draped around a pulley rotatably supported by said carrier.
Such a conventional arrangement, in which the wire is attached to the housing of the image processor with the interposition of the coil spring or the like, may be accompanied with an apprehension that an external force such as vibration or shock caused, for example, during transport of the image processor might unintentionally move the carrier so as to pull the wire and thereby stretch said coil spring. Stretching of the coil spring may cause the wire to slacken and to slip from the guide pulleys. Various factors, such as the level of wire tension, are usually adjusted, for example, before shipping of the image processor so that the carrier may be driven in a predetermined manner after the image processor has been installed on its actual site of service. However, should the wire slip from the guide pulleys during transport of the image processor, said factors of the wire including its tension and, therefore, the manner in which the carrier is driven must be readjusted on the actual site of service. Operation of such readjustment is very troublesome and accordingly there is a serious need for an effective improvement to avoid the wire from slipping from the guide pulleys, for example, during transport of the image processor.